I've tried coffee and guava. The coffee is good; however, it pretty strong stuff. You have to be very careful with the coffee as it is easy to ruin a cook if you use it like hickory or other 'mainstream' woods. Guava, for me, was at the other end of the spectrum, not a whole lot there, but maybe I didn't use enough.
Peach is currently my favorite smoking wood, and I buy it here: http://www.fruitawoodchunks.com/
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